This invention is directed to apparatus for measuring large diameter rolls, and in particular, it is directed to a roll diameter measuring device having an LVDT probe in combination with an internal processor programmed to provide a direct roll diameter display.
The space between the lower and upper working rolls in a rolling mill stand define a roll gap that must be adjusted to transfer a proper rolling force from the working rolls to the incoming metal plate or strip product being manufactured. To more accurately control the thickness of the metal product, it is necessary to monitor the roll gap using any one of a variety of measuring devices known in the art. In accordance with the known state of the art, such roll gap measurement devices calculate and adjust the roll gap, and hence the rolling force, based upon the known diameters of working and backup rolls supported within the mill stand. Therefore, it follows that in order to more accurately control both the roll gap and product quality, it is necessary to be able to determine correct roll diameter to insure product quality. Accurate roll diameter measurements are necessary to set and control roll gap in both hot and cold rolling mills as well as in other industrial applications. For example, similar accuracy is required in continuous caster rolls that contain and control the path of the cast product. Similarly, it is necessary to accurately determine original and refinished roll or shaft diameter in other industrial applications including rolls in paper and plastic manufacturing processes, in large shafts used in electrical generators, and drive shafts used in marine applications. Therefore, although the present invention may be directed to metal rolling mill applications, it should be understood that the scope of the invention extends into other manufacturing processes and industries.
In a rolling mill that manufactures steel plate and sheet, large diameter rolls are used to deform, contain, and/or manipulate the product being manufactured. For example, at our rolling mill operations, a new work roll will measure between about 30-37 inches (76.20-93.98 cm) in diameter depending upon the particular mill stand. The backup rolls measure approximately 50-60 inches (127.0-152.4 cm) in diameter when they are new. Similarly, new continuous caster rolls that contain and control the liquids strand moving through the roll segments positioned below the caster mold measure somewhere between 4-12 inches (10.16-30.48 cm) in diameter. Such industrial rolls are systematically refinished throughout their service life to insure that they continue to deliver a product having good surface quality. Refinishing includes surface grinding along the roll diameter to remove any roll defects, for example pits, burrs, gouges, or wear spots that may reduce product quality, and the rolls are periodically refinished until the diameter has been reduced to a size where the roll is no longer suitable for service. Typically, roll service life ends when the roll diameter is reduced to about 90% of its original roll diameter size. For example, at our Steckel Mill, a new work roll should have a 32 inch (81.28 cm) diameter. When refinishing operations have finally reduced the roll diameter to 30 inches (76.20 cm), the roll is considered scrap and is removed from the rolling line. Therefore, in this instance, roll service life ends when the diameter is reduced to about 93.75% of the original roll diameter. Roll service life criterion will vary from mill to mill.
As clearly illustrated above, the working diameter of industrial roll and the like continually changes throughout service life. Therefore, in rolling mill applications, when operators manually adjust a roll gap, or when they calibrate a device that automatically adjusts the roll gap, it is critical for operators to have an accurate diameter reading of each roll mounted within a particular mill stand. It is also critical to the manufacturing process to have such accurate roll diameter information available from the time a new roll is installed in the mill stand and throughout its service life.
In past roll refinishing operations, both pre-grinding and post-grinding roll diameter measurements were taken with either large diameter micrometers or with Pi (xcfx80) tapes. Large diameter micrometers are heavy and awkward to use. They require considerable skill and xe2x80x9cfeelxe2x80x9d on the part of the user in order to take accurate readings, and as a result, measurement readings are often not repeatable, particularly if the measurements are taken by different people. Such error is a constant source of concern because it may result in faulty roll gap adjustments and out-of-spec product. On the other hand, Pi tapes are also problematic because operators need to encircle the large roll circumference with the tape and read the roll diameter measurement directly from the calibrated scale that appears on the face of the tape. Again, user skill is a requirement to take accurate Pi tape measurements. Any tape sag or misalignment along the circumference of the roll will result in measurement error and inaccurate roll gap adjustments. Therefore, there is a long felt need within the art, to develop a simple large diameter measuring device that overcomes the problems and limitations set forth above.
It is therefore an object of the present invention to provide a diameter-measuring device having improved measurement repeatability.
It is a further object of the present invention to provide a measuring device that is not dependent upon user skill for accuracy.
It is another object of the present invention to provide a measuring device capable of measuring an increased diameter range as compared to measuring devices of the past.
It is a further object of the present invention to provide a measuring device having replaceable sensor probes to increase diameter measuring range.
It is an additional object of the present invention to provide a measuring device that displays direct readout corresponding to the diameter of a measured object.
It is still another object of the present invention to provide a measuring device that includes a sensor probe in combination with a microprocessor that generates an LCD display corresponding to the diameter of a measured object.
Other objects and advantages of the present invention will become apparent as a description thereof proceeds.
In satisfaction of the foregoing objects and advantages, the present invention provides a measuring apparatus having a frame adapted to receive an interchangeable sensor assemblies and a centering head adapted to engage then object being measured. The interchangeable sensor assemblies include a sensor probe that is biased in an outward direction therefrom so that its tip end contacts the measured object, and the probe includes means to generate a signal indicative of its tip end position. The frame portion of the measuring device also includes a microprocessor capable of receiving the sensor probe signals, and the microprocessor is programmed to provide an output display that corresponds to the diameter of the object.
The diameter of the object being measured is determined by storing in the microprocessor a calibrated gap distance in the based upon a first sensor probe signal indicative of probe tip position, calculating a measured gap distance based upon the stored calibrated gap distance and a second first sensor probe signal indicative of probe tip position, and determining diameter of the object based upon the calculated measured gap distance.